Q: ActiveStorage DiskService directory sharding

Hello list,

I’ve noticed ActiveStorage::Service::DiskService does two levels of directory sharding for Blob pathnames:

$ tree storage/ storage/ ±- aa/ ±- bb/ > ±- aabb00… ±- cc/ ±- aacc11…

However, when it comes to variants, the sharding is circumvented:

$ tree storage/ storage/ ±- aa/

±- bb/

±- aabb00… ±- cc/ ±- aacc11… ±- va/ ±- ri/ ±- variants/ ±- aabb00…/ ±- ±- aacc11…/ ±-

Should sharding exclude variant/ key prefixes? Maybe the directory layout can look like this:

$ tree storage/ storage/ ±- aa/

±- bb/

±- aabb00… ±- cc/ ±- aacc11… ±- variants/ ±- aa/ ±- bb/ ±- aabb00…/ ±- ±- cc/ ±- aacc11…/ ±-

This might not actually a problem at all, as the limiting factor on ext4 file systems is the inode index (which allow directories to contain ~10 million entries with 32 character long names (reference); the Base58 blob id is only 24 characters long). I guess with ZFS it’s even less of a problem.

I was going to create an issue for this, but this might actually be expected/desired behaviour. I’m also not sure if this is a bug or feature request either. I know changing this will cause some headache. I’m primarily looking for other opinions.

Kind Regards,


On the first look I would like your layout more (as something I would expect or design myself). However, I don’t know any background on why is this like it is.

Dne úterý 27. srpna 2019 13:24:02 UTC+2 Dominik Menke napsal(a):